Generally, a large-scale wireless local area network (WLAN) uses a centralized network architecture and includes an access controller (AC) and an access point (AP). Except for providing a radio frequency signal, the AP basically does not have management and control functions. Therefore, to implement a function of a wireless local area network, besides an AP, a device AC having management and control functions is also required. Primary functions of the AC are to manage and control all APs on the wireless local area network, and the AC and the APs cooperate to jointly implement the function of the wireless local area network. One AC can control and manage multiple APs. After receiving packets sent by a station (STA), APs transmit the packets of the STA to an AC in a tunneling manner, and the AC performs centralized forwarding processing on these packets.
In a centralized network architecture, an AP needs to be managed by an AC; therefore, if a fault occurs in the AC, the AP cannot work independently, resulting in a breakdown of a wireless local area network.